Point Loma 
In more than 700 scuba dives off La Jolla Shores, Terry Strait had never encountered a deep-water current like the one that slammed into him and his buddies yesterday morning about 250 yards from the beach.

As the four divers swam roughly 60 feet below the surface along the edge of La Jolla Canyon, they noticed a wall of sand rushing toward them from the southwest.

“The current was really pushing us,” said Strait, 41, of Kensington. “We tried to swim lateral to it but couldn't get out of it.”

They held on to the edge of the cliff to avoid being pushed farther out to sea. The group slowly swam against the flow toward the surface and finally broke free at a depth of 15 feet, Strait said.

The strange and previously unknown current occurred in a normally placid area of water, said lifeguards and a marine expert at the nearby Scripps Institution of Oceanography. It was noticed by other divers in the area over several hours starting around 6 a.m., but not by swimmers on the surface of the water.

Though no one was injured by the flow, lifeguards at the beach cautioned divers about the current, lifeguard Sgt. John Everhart said.

“It seems like it was a relatively short-lived event,” he said. “This won't change our planning for the Fourth of July weekend.”

Strait said years of diving experience helped him and the others in his group stay levelheaded during yesterday's incident.

“If a new diver had been out there, they would have freaked,” he said.

The current puzzled divers and lifeguards.

“It certainly wasn't something that lifeguards have heard about,” Everhart said. “I have no idea how it could occur.”

Richard Seymour, a scientist at Scripps, came up with a theory after reviewing reports of wave patterns and weather conditions during the flow.

Seymour quickly eliminated three possibilities — an avalanche of sand in the canyon, an extreme upwelling event triggered by strong northerly winds or a sudden movement of water caused by a big change in atmospheric pressure.

During normal current patterns, waves move up the coast from the south, Seymour said. Point La Jolla, which juts into the Pacific Ocean, serves as a natural breaker that largely protects the north-lying La Jolla Bay from those waves.

But the wave track shifted slightly yesterday morning — coming more from the southwest, Seymour said. The change was enough to allow waves to wrap around Point La Jolla and move into the bay, where they collided with a large pool of sedentary water that bounced them back out to sea.

Divers swimming around the edge of La Jolla Canyon were in the direct line of that deflection, Seymour said.

“The currents around La Jolla were very strong,” he said. “The intensity of this event was probably produced by a group of very big waves.”

Strait, an amateur underwater photographer who dives in La Jolla Bay three days a week, said his encounter with the freak current hasn't dampened his passion for the water.

“I'll probably go back out there tomorrow,” he said. “I have respect for the ocean. I constantly remind myself that I'm not really supposed to be out there underwater and that the ocean wants to kill me.”